In this paper, we tried to evaluate the contact angle for a droplet on the solid surface based on elasticity theory for the elastic bulk and thermodynamics. At first, we provided the surface tension of the solid which was a direct rule factor of the wettability as the function of strain in the imaginary layer with thin finite thickness τ by using elasticity theory. And by applying this function to the thermodynamic system consisting of a droplet on the solid surface, we get the equations to be satisfied with the contact angle of the droplet. Solutions of these equations showed good agreement with the experimental contact angle surveyed for droplet on Alkyl Ketene Dimers (AKD) which had fractal structure.